For the Obama administration, the motivation for the moves to normalize relations with Cuba is clear. The embargo against Cuba is increasingly unpopular, even in parts of the Cuban-American community that long supported it, and the president has been eager to find areas of both foreign and domestic policy where he can act without cooperation from Congress. But what's driving this move on the Cuban side?
For one thing, last week's prisoner exchange, involving three of the five intelligence officers convicted of espionage in Florida in 2001, was a major propaganda victory. "Getting the rest of the Cuban Five back has been a huge priority for Raúl Castro," Julia Sweig, director of Latin America studies at the Council on Foreign Relations, said.
Underlining the iconic status the Cuban Five have taken on during their captivity, Castro referred to the men by their first names during his speech Wednesday, saying, "As Fidel promised on June 2001, when he said, 'They shall return!' Gerardo, Ramon and Antonio have arrived today to our homeland."
There are two more looming factors guiding Raúl Castro's thinking. One is that the 83-year-old leader plans to step down in 2018, meaning the country will not be governed by a Castro brother for the first time since 1959.
This is likely to be a fraught transition for Cuba's Communist Party. As part of what he calls the "systematic rejuvenation" of a party long led by aging veterans of the revolution, Castro last year replaced his 82-year-old first vice president with 52-year-old Miguel Díaz-Canel, making him the most likely successor. Díaz-Canel, though, is a relative unknown and won't come into power with much credibility if the party can't deliver economic growth.
The modest economic reforms made thus far, including the loosening of restrictions on private property and independent businesses, haven't done enough, delivering just 1.4 percent GDP growth this year due to what the country's economy minister called "internal insufficiencies." As Sweig put it, more dramatic steps "need to be implemented, and fast," if Castro's chosen successors are going to manage the transition.
"I do think that they're trying to lay the groundwork for a process of change in which they can keep their scalps and guide the country toward a more sustainable political system," said Christopher Sabatini, senior policy director and chairman of the Cuba Working Group at the Americas Society/Council of the Americas.
The other big factor at play here is the turmoil in Venezuela. The South American nation threw the tottering Cuban economy a lifeline during the regime of Hugo Chávez, providing the island with 100,000 barrels of oil per day. Today, in the aftermath of Chávez's death and bruised by political turmoil and the plummeting price of oil, Venezuela's economy is in chaos and the government is on the verge of defaulting on its debt.
"You don't need to be a capitalist to realize that Venezuela's economy is in very dire straits," said Sabatini. "It's getting worse literally by the day. So they're going to lose that benefactor."
Add the Venezuela situation to the Castros' advancing years and you can understand what's driving Raúl toward a more accommodating stance. "It would be the height of poor planning to think that those two things could happen and the country would be okay," Sabatini said. Another factor may be Fidel's gradual retreat from politics. The 88-year-old, who is formally retired but thought to still be influential, makes only rare public appearances these days. (Fidel, or someone writing under his name, does still regularly weigh in on global affairs in columns for Cuba's state newspaper.)
While the official line from Havana is that there's no daylight between the politics of the two brothers, it does seem like the father of the revolution is either less of a factor than he used to be or has mellowed somewhat with age.
"I don't see today's version of Fidel Castro opposing this," said Sweig. "But if we were having this conversation when Fidel was still in power — the 1998 version of Fidel Castro — it might be different."
Another X factor is presumed successor Díaz-Canel, who wasn't even born at the time of the Cuban Revolution and kept pretty quiet since rising to his current position last year.
"Díaz-Canel is somewhat of a mystery, but there is an element of a new generation that recognizes that the country has to change," said Sabatini. All the same, speculation about massive political transformations is probably premature.
"We haven't even gone from Stalin to Khrushchev yet," Sabatini said, comparing such speculation to Cold War-era "Kremlinology." And in any case, Díaz-Canel certainly wouldn't have been given his current position if Raúl didn't see him as a loyal communist.
Assuming the seemingly spry Raúl remains healthy, he has three more years to manage the transition. Sweig said that while Cuba is unlikely to democratize anytime soon, last week's developments mean the government will take a more pragmatic approach.
"I'm not talking about multiparty democracy, but I am talking about the pulling back of the Communist Party from government, the receding of ideology, the creation of a well-functioning economy and more open society," she said. "All of that will happen better with a normal relationship with the United States."
Joshua Keating writes on international affairs for Slate.
© 2014 Slate